Input.mousePosition

설명

The current mouse position in pixel coordinates. (Read Only)

The bottom-left of the screen or window is at (0, 0). The top-right of the screen or window is at (Screen.width, Screen.height).

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour {
    public GameObject particle;
    void Update() {
        if (Input.GetButtonDown("Fire1")) {
            Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition);
            if (Physics.Raycast(ray))
                Instantiate(particle, transform.position, transform.rotation);
        }
    }
}